Apparatus for analyzing the influence of additive reagents upon the coagulation of blood and related methods

ABSTRACT

A sample of blood is divided into a plurality of isolated test chambers. The blood is mixed with additive reagent having previously been measured into each test chamber. A clot detector and analyzer system determines the time required for the blood-reagent mixture in each chamber to form a clot. In a first mode of analyzer system operation there is recorded the time required for a selected number of clots to be detected. A second mode of operation identifies those chambers in which clots have been detected within a specified time interval.

This is a divisional of application Ser. No. 281,661, filed on 7/9/87and now U.S. Pat. 4,443,408 issued on Apr. 17, 1984.

BACKGROUND OF INVENTION

This invention relates to the analysis of blood coagulation time as itis influenced by differing concentrations of additive reagents, and moreparticularly to apparatus and methods for performing the analysis ofblood coagulation time.

It is well-known in the practice of clinical medicine to inhibit thecoagulation of blood by administering various anticoagulant medications.One such medication, heparin, is particularly important because itseffects as well as its neutralization by the agent, protamine, areessentially instantaneous. Widely used in early treatment ofthromboembolic disease, herapin's most noteworthy applications are inthe fields of extracorporeal circulation such as cardiovascular surgeryand hemodialysis. An excellent article giving a survey of the herapintherapy field is entitled "Inappropriate Response to Herapin" by H. B.Soloway, Diagnostic Medicine, Sept./Oct. 1979, pages 31-33.

Protocols for heparin therapy administration and control are usuallybased upon a prescribed prolongation of coagulation time as determinedby some clot timing technique. Protocols which prescribe a heparin dosebased upon patient's sex, weight and height fail to account forvariations in patient response to herapin. Such problems and a proposedsolution are discussed by Bull, et al., "Heparin therapy duringextracorporeal circulation: I. Problems inherent in existing heparinprotocols; II. The use of a dose-responsive curve to individualizeheparin and protamine doseage," 69 J. Throacic Card. Surg. 674-689(1975). Application of the method of Bull, et al to the system describedin U.S. Pat. No. 3,695,842 issued to Michael D. Mintz, the inventorherein, is explained by Kersting and Rush, "A Simple IndividualizedMethod for Dose-Responsive Heparin and Protamine Administration," 11 J.Extra-Corp. Tech. 56-60 (1979). Briefly described, the dose-responsivetechnique is an in vivo method in which coagulation time tests areperformed on blood samples taken before and after a patient has beengiven one or two bolus heparin infusions. The resulting data, plotted asheparin vs coagulation time, are used to determine current heparinlevel, maintenance dose requirement and protamine neutralization doseimplied by subsequent coagulation time tests.

U.S. Pat. No. 4,000,972 entitled MEASURING SYSTEM FOR THEPHARMACOLOGICAL MANIPULATION OF THE COAGULATION MECHANISM IN BLOOD ANDFOR THE ELAPSED COAGULATION TIME issued to Braun, et al. on Jan. 4,1977, describes a system and method of protamine titration ofheparin-medicated blood in which a single blood sample is divided into aplurality of test chambers. Thereafter, differing amounts of protamineare injected into each chamber and mixed with the blood aliquots. Thetest is terminated upon first observation of clotting in one of thechambers. The protamine concentration in the chamber thus identified isdesignated by the system as the neutralizing protamine concentration. Acalculator section of the system subsequently interprets this data, inconjunction with certain operator-input patient and protocol data toyield the patient's specific protamine dose requirement. By equating theneutralizing protamine concentration to heparin concentration andcomparing this implied level of heparinization with the operator-input,heparin maintenance level, the calculator section computes a heparinmake-up dose for the patient. This prior art system has the advantagesof performing analyses on a single sample of blood. Test results areessentially independent of the temperature conditions to which thevarious test chambers are simultaneously subject, and they are readilyunderstood by the operator.

The system of Braun, et al. has several disadvantages. First, thecoagulation time reported by the analyzer is representative of theneutralized sample after addition of protamine, not of the blood as itmay be flowing in patient or extracorporeal circuit. Second, the basisfor selecting the first observed clotted chamber as that containing theexact neutralizing protamine concentration is, as stated by theinventors, "too much protamine results in anticoagulated blood." Whilethis statement is generally accepted as factual for large concentrationsof protamine, Perkins, et al., "Neutralization of heparin invivo withprotamine; A simple method of estimating the required dose", 48 J. Lab.& Clin. Med. 223-226 (1956) has shown that protamine concentrations ofas much as three times the neutralizing concentration in heparinizedblood may exhibit essentially identical coagulation times. In-as-much asall clot detectors are characterized by some degree of statisticaluncertanty, it will be seen that the first clotted blood specimen inthis prior art system may randomly contain protamine concentrationsbetween one and three times the desired levels.

Another disadvantage of this prior art system is that it is limited touse in heparin therapy protocols that seek to maintain or controlheparin concentration. It has been shown by several researchers (see forexample, Berg, et al., "Monitoring heparin and protamine therapy duringcardiopulmonary bypass by activated clotting time" 11 J. Ext. -Corp.Tech. 229-235 (1979), however, that the heparin dose required to prolongcoagulation to a specific activated clotting time value of say 480seconds may vary from 100 to 700 units per kilogram of body weight.Hence, control of blood heparin concentration alone may be inadequate toprevent clotting during critical extracorporeal procedures.

OBJECTS OF THE INVENTION

Accordingly, it is the object of the present invention to provide animproved apparatus for reliably measuring coagulation time, determiningthe heparin concentration in blood necessary to prolong coagulation timeto specified values, and determining the protamine concentrationrequired to neutralize the heparin in heparinized blood.

It is a further object of the present invention to provide apparatus formonitoring and controlling heparin therapy that are compact, easilyoperated and easily interpreted by the operator.

These and other objects relate to an improved apparatus which is easy touse and fabricate as well as efficient methods for performing suchmeasurements.

SUMMARY OF THE INVENTION

A system and method of analyzing the influence of coagulant andanticoagulant reagents or medications on the coagulation time of blood.The foregoing objects are obtained in accordance with the presentinvention whereby a sample of blood, normal or anti-coagulated, isdivided by known volumes into a plurality of numbered test chamberscomprising a test cartridge, there having been previously measured intoeach test chamber coagulant or anti-coagulant reagents such that thereagent concentration of the blood-reagent mixture in a chamber may becalculated by multiplying a predetermined numerical constant and theassigned cell number.

According to the present invention a simple timer or stop watch isactivated by an operator when the cartridge and blood-reagent mixture isin a condition ready to start the analysis and the test cartridge ismanually agitated. Upon elapse of a predetermined or given time intervaleach test chamber of the cartridge is inspected for clotted blood. Theresults, identified by chamber number, are recorded. If, for example,the premeasured reagent is an anti-coagulant, the concentration of suchanti-coagulant required to prolong coagulation to at least the giventime interval is obtained by identifying the lowest numbered testchamber in which no clot has been observed. The mathematical product ofthe chamber number thus identified and the predetermined constantmanifests the required anti-coagulant concentration.

Another aspect of the present invention provides a multi-chamber testcartridge which is inserted into an automatic analyzer system. Thesystem includes a plurality of data channels each associated with aseparate clot detector, electronic memory latch and a visual paneldisplay indicator. Each chamber of the test cartridge is cooperativewith one channel of the analyzer and is uniquely identified on the paneldisplay. A blood level detector is provided to start the analysis whenit is sensed that all of the test chambers have been filled with therequired volume of blood. An electric motor coupled to the testcartridge provides mechanical rotation to mix the blood and reagent inthe various test chambers. A timer and timer panel display providestimed control functions and readout during the analysis. An end pointcounter maintains a record of the number of test chambers in which clotshave been detected during the analysis.

Digital comparators continuously compare timer and end point counterdata with operator selected panel switch settings, thereby to select theanalyzer mode of operation and operating parameters.

The analysis is preceeded by the operator selecting panel switchsettings and test chamber reagents according to a desired procedure. Thetest cartridge with premeasured reagents is then placed in the analyzerinstrument. A sample of medicated or normal blood is thereafter injectedinto the test cartridge, where it is automatically divided into thevarious individual test chambers. On filling all of the test chambersthe blood overflows into an auxillary chamber where it is sensed by theblood level detector. The resulting signal initiated by the blood leveldetector causes the latches and timer to be reset and the timer to starttiming the analysis. The reset logic enable latch causes the clotdetectors to be activated and energizes the motor, which agitates thetest cartridge causing the blood and reagent in each chamber to bemixed. The first time a clot is detected in a given test chamber, thecorresponding panel display indicator is energized and the end pointcounter incremented. The analysis is terminated when either the timer orthe end point counter comparators register equality with correspondingpanel switch settings.

The following table summarizes analytic capabilities of the apparatuswhich are important in maintaining control of heparin anti-coagulanttherapy during surgical procedures.

    __________________________________________________________________________    Analysis     Reagent                                                                             End of Analysis Condition                                                                    Interpretation                              __________________________________________________________________________    Average coagulation time                                                                   none  End point counter has counted                                                                Approximate average coagulation                                clots in half of total test                                                                  time displayed by timer panel                                  chambers       display                                     Heparin concentration                                                                      heparin                                                                             Timer registers perscribed time                                                              Required heparin concentration              requirement        interval for coagulation pro-                                                                equal to product of lowest                                     longation      chamber number not registering                                                clot on panel indicators and                                                  predetermined numerical constant            Protamine concentration                                                                    protamine                                                                           Timer registers time interval                                                                Required protamine concentration            required to neutralize                                                                           equal to predetermined normal                                                                approximately equal to product              heparin in heparinized                                                                           or unheparinized coagulation                                                                 of lowest chamber number register-          blood              time for the same blood as                                                                   ing clot on panel indicators and                               determined by prior analysis                                                                 predetermined numerical                     __________________________________________________________________________                                      constant                                

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of the inventionillustrating a one-piece test cartridge comprising five test chambers.

FIG. 2A is a cross-sectional view of the cartridge of FIG. 1 showing onechamber, with the cartridge in a partially closed condition.

FIG. 2B is a cross-sectional view of the cartridge of FIG. 1 showing onechamber, with the cartridge in a closed condition.

FIG. 3A is a cross-sectional view of the test cartridge of FIG. 1showing the process of injecting a blood sample.

FIG. 3B is a cross-sectional view of the test cartridge of FIG. 1showing the test chambers closed immediately following blood sampleinjection.

FIG. 3C is a cross-sectional view of the test cartridge of FIG. 1showing the cartridge inverted for timing an analysis.

FIG. 3D is a cross-sectional view of the test cartridge of FIG. 1showing the cartridge in its upright orientation with clotted blood insome of the test chambers at the conclusion of the analysis.

FIG. 4 is a perspective view of a second embodiment of the inventionillustrating the analyzer with a test cartridge partially inserted inthe test well.

FIG. 5A is a cross-sectional view of the test cartridge of the secondembodiment showing the process of dividing the sample as it is injectedinto the cartridge.

FIG. 5B is an internal view of the test cartridge of the secondembodiment showing auxillary or overflow chamber, its relationship tothe blood level detector and blood entering the chamber.

FIG. 6A is an internal view of the test cartridge of the secondembodiment showing a test chamber, its relationship to the clot detectorand an unclotted blood sample within the chamber.

FIG. 6B is an internal view of the test chamber of FIG. 6A showing thechamber, its relationship to the clot detector and a partially clottedblood sample within the chamber.

FIG. 7 is a schematic block diagram showing the electronic logic of theanalyzer of the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there is shown a cartridge assembly 10 which can beused to analyze the coagulation time of blood when subjected to anadditive reagent.

A base plate is divided into two sections as a right (R) and a leftsection (L) by means of a longitudinal groove 13. Located on the rightside of the groove 13 are a plurality of first cylindrical chambers ormembers 11a. Located on the left side (L) of the groove 13 are a secondplurality of cylindrical chambers or members 11b.

In FIG. 1, there is shown five chambers designated as 11a and fiveassociated chambers designated as 11b. It is of course understood thatthe number of such chambers may be varied and hence more or less thanfive chambers can be included. However, as will be explained, eachchamber as 11a is associated with a corresponding chamber as 11b. Thechambers 11a have a top depression 20a with sloping sidewalls which isadapted to receive the extending tapered cylindrical flange 20bassociated with each chamber on the left side as 11b. The depressionsassociated with chambers 11a communicate with one another by means of asurface channel 19 which acts as a trough for a blood sample to bereceived by the assembly as will be explained.

In this manner, upon folding or pivoting the cartridge 10 about thegroove 13, each section 20b of cartridge 11b is inserted into thecorresponding depression of its associated chamber 11a. To hold theassembly in the folded position, an extending seal 14 is disposed aboutone section of the assembly 10 R or L and serves to lock or hold acartridge assembly in position whereby the volume 12a and 12b of eachchamber communicate with one another. The seal 14 coacts with the edge15 on the opposite section. The entire assembly shown in FIG. 1 can befabricated from a semi-rigid transparent plastic and formed as anintegral unit.

Referring to FIG. 2B, there is shown a transverse cross sectional viewof the cartridge 10 depicting members 11a and 11b in a partially closedposition. FIG. 2B depicts the members 11a and 11b in a fully closedposition with seal 14 coacting with edge 15 to provide the locked state.In FIG. 2A numeral 16 references a premeasured additive reagent appliedto to the inner surface 17b of chamber 11b.

As can be ascertained from FIGS. 2A and 2B, the inner diameter 12b ofmember 11b is somewhat larger than the inner diameter 12a of chamber11a. In this manner, a peripheral shelve 21 is formed during the closedposition as shown in FIG. 2B.

Referring to FIGS. 3A to 3D, there is shown a series of schematicdiagrams which depict the sequential operation of the above describedapparatus in performing a measurement of coagulation time. In thefigures the chambers 11a and 11b are shown generally in cylindrical formand the exact details as described in FIGS. 1 and 2 regarding thedepressions and flanges have been omitted for the sake of clarity. Inany event, the same reference numerals are employed to designatecorresponding structure.

Referring to FIG. 3A, there is shown a cross-sectional view ofcartridges on the right side as 11a. A quantity of heparinized bloodsample 30 is injected by means of a syringe 31 into one of the testchambers 11a. As the test chamber is filled, the blood overflows and isdirected via the trough 19 into the adjacent test chamber which thenbecomes filled with the heparinized blood sample. Thus this process iscontinued until all chambers are filled via the above described action.

Once this occurs, the cartridge 10 is closed as shown in FIG. 3B withthe inner volume of members 11a communicating with members 11b. Thecartridge assembly 10 is then locked by means of seal 14 to form aliquid type barrier as depicted in FIG. 3B.

Also shown in FIG. 3B is the additive reagent 16 which is secured to theinner surface of members 11b as explained. The reagent 16 in eachassociated chamber 11b is premeasured in incremental quantities andsecured to the wall by a vacuum drying technique or other suitablemethod.

The user then inverts the locked assembly 10 as shown in FIG. 3C andagitates the assembly for several seconds to cause the blood 30 torapidly flow between the volumes of the coacting chambers. A timer whichmay be a stop watch or other conventional device is simultaneouslystarted at the commencement of the agitation procedure. The agitationcauses the blood in chambers 11b to react with the reagent 16. The timeinterval selected for analysis is a prescribed interval which isselected by the operator according to a desired procedure to beperformed. At the conclusion of this time interval, the cartridge isagain inverted as shown in FIG. 3D and hence chambers 11a are in thelower most position. Blood that has clotted (reference numeral 32) isnow unable to flow into chambers 11a due to the mechanical bridging atthe blood-air interface 33 as supported by the shelf 21 which isanalogous to the annular ridge 18a of FIG. 2A and 2B.

It will be understood that additive reagent 16 may be provided inprepackaged form as a freeze-dried or evaporation dried material that isreadily soluable in blood and affects the coagulation time of blood 30.Such materials may for example include heparin, protamine,sodium-citrate or calcium chloride. In the case of anti-coagulants suchas heparin the prescribed time interval of the analysis might be 480seconds, as recommended by Bull, et al. In such example the test chambercontaining a blood-heparin mixture adequate to prolong coagulation to atleast the 480 seconds is that chamber containing the least amount ofheparin for which no clotted blood is observed after the 480 secondinterval. If a neutralizing protamine concentration is sought theprescribed time interval of the analysis might be a typical activatedcoagulation time of 135 seconds. At the conclusion of such time intervalthe neutralizing protamine concentration is that contained in the testchamber having the lowest protamine concentration in which clotting isobserved.

It will be recognized in both the examples of anti-coagulant andneutralizing reagent additives that the (analyist) may simply determinepatient dose by forming the mathematical product of chamber number,patient blood volume and a constant. The constant in such case is theincremental additive concentration in the test chambers of thecartridge. That is, the blood reagent concentration in chamber 1 is oneconstant, the concentration in chamber 2 is two constants, etc. Suchconstants are well-known in that a user would know how to select theconstant.

Referring to FIG. 4, there is shown a housing including a front panelconfiguration of automatic apparatus which will perform a bloodcoagulation measurement employing a similar method as above described.As will be explained, the automatic test apparatus employs a unique testcartridge 50 which is inserted into a test well 41 associated with theanalyzer housing. The front panel of the analyzer includes a digitaldisplay 42 which may consists of a seven segment LED or LCD modulecapable of displaying the running time during an analysis. Also locatedon the front panel are a plurality of visual indicators 43 which, aswill be described, indicate the status of detected clots in various testchambers.

In this manner, the display 43 will indicate the exact test chamber inwhich a clot occured during a test procedure. Also depicted is a bank ofthumb wheel switches 44. As will be explained, the switches 44 are BCDcoded to allow a direct interface with the electronic circuitry of theanalyzer. The switches 44 are set by the operator or user to specify agiven time interval during which the analysis is to be performed.

Another switch 45 is also a thumbwheel switch and has ten positions. Theswitch 45 is decimally coded to interface with the correspondingcircuitry. The operator uses switch 45 to set the switch to a numberfrom 1 to 10(0) to thereby select or establish an analysis completioncriterion which terminates the operation of the analyzer when the totalnumber of channels identifying clots in the respective test chambersequals the switch setting.

As seen in FIG. 4, the cartridge 50 has an input aperture 52 forpermitting entry of a syringe. The aperture 52 is integrally formed withan outstanding tab 48. The tab 48 will extend from the well 41 to allowa user to remove the cartridge 50 when it is fully inserted into thetest well 41.

Referring to FIG. 5A, there is shown a longitudinal cross-sectional viewof a test cartridge as 50. The cartridge 50 is fabricated from atransparent rigid plastic and has a plurality of coaxial annular testchambers as 51. Each test chamber 51 is separated from an adjacentchamber by means of annular walls 56. Thus as seen from FIG. 5, the testcartridge 50 provides a plurality of individual test chambers.

A blood sample 80 is injected by means of a syringe 81 which is insertedinto the aperture 52. The aperture 52 has a tapered inner surface 53 toengage with the Luer-fitting syringe nozzle 87. A baffle 54 is locatedabout the aperture 52 and operates to divert the blood sample 80 torestrict flow into the first input chamber or entry chamber 55.

As can be seen from FIG. 4, the cartridge 50 is emplaced in the well 41.It is held at an angle to allow blood to flow from one chamber to thenext under the influence of gravity.

In this manner, the annular walls 56 separate blood into the respectivetest chambers as 51. A last blood chamber is designated as chamber 57and is associated with a light source 58 on one side and a photo sensor59 on the other side.

As one can ascertain, a quantity of blood which enters chamber 57 willserve to blocklight from source 58 to thereby provide an indication thatall chambers 51 above chamber 57 have been filled with a blood sample.Also shown associated with cartridge 50 is keyed cavity 60. The cavity60 is provided to engage a rotational drive means associated with amotor and hence to rotate the cartridge 50 about its axis. There aremany techniques for providing a rotational motion to a cartridge as 50contained within a cylindrical cavity as test well 41.

Also depicted in FIG. 5A is a vent or aperture 82. The aperture 82allows air to escape from the confines of the cartridge 50 as blood isbeing injected. The release of air in this manner prevents blood fromsquirting out or being thrusted out of the main aperture 52.

Referring to FIG. 5B, there is shown a cross-sectional view of theoverflow chamber 57 with blood sample 80 blocking the light projectedfrom source 58 to the photo sensor 59. This, as will be explained,provides a signal which causes the analyzer to begin operation.

Referring to FIG. 6A, there is shown a cross-sectional view of a typicaltest chamber 51 with a blood sample 80 in the lower position. Eachchamber as 51 is associated with a separate light source as 62 and aseparate photo sensor as 63. As indicated, the cartridge 50 istransparent and in the position shown in FIG. 6A, light emanating fromsource 62 impinges upon the photo sensor 63.

In FIG. 5A the upper walls of each chamber of the test carriage 50 havesecured thereto a predetermined amount of a dried reagent as 85. Theamount of reagent in each test chamber varies incrementally as describedabove. Hence as the cartridge 50 is rotated, the blood sample 80 willcontact the reagent 85 and mix therewith.

Referring to FIG. 6B, a rotation in the direction of arrow 61 may beclockwise or counter clockwise. Clotted portions 82 of blood sample 80are, by natural or surface roughness adhesion processes, caused toadhere to the inner surface 64 of the test chamber wall. The rotation 61causes the clotted blood 82 to be drawn up and operates to effectivelyblock the light from source 62. Thus, the blocking of the lightindicates the presence of a clot and this condition is detected by theelectronic assembly of the analyzer as will be explained in detail byreferring to FIG. 7.

FIG. 7 is a schematic block diagram depicting the electronic logic ofthe analyzer system as for example, included in the housing of FIG. 4.Shown in FIG. 7 is a schematic representation of the test cartridgehaving the plurality of test chambers 51. The cartridge 50 is insertedinto a well which may comprise a cylindrical cavity for receiving thecartridge. Located adjacent each test chamber as 51 is a series of lightsources 62 and associated photosensors 63. In this manner each testchamber as associated therewith has its own light source as 62 and anassociated sensor 63. Each photosensor is coupled to a respective latch71.

Essentially, the latch is a bistable circuit which will produce onelogic value during a change in impedence of the sensor 63 due to theblockage of light. The latch operates to store this change of stateuntil it is reset. There are many examples of data latches as 71 knownin the art and which will operate in conjunction with photosensors toprovide one output such as a logic 1 for the blockage of light andanother output such as a logic 0 when light propogates to the sensor 63via the source 62. The output of each latch is coupled to an end pointcounter 72. The counter 72 operates to monitor each latch to determinewhether there is a change of state. This is easily implemented by meansof suitable decode gates associated with counter 72 and responsive tothe output state of latches as 71. A data comparator 73 has one inputcoupled to the counter 72 and one input coupled to the thumbwheel switch45. The output from switch 45 constitutes ten parallel lines eachindicative of one setting as 1 to 10(0). Hence, the comparator 73 willprovide an output on lead 80 when the comparator detects a conditionwhere the number of latches 71 designating a clotted sample equals thenumber programmed into the comparator 73 via switch 45. For the settingshown when five test chambers 51 of the cartridge 50 have clottedsamples the data comparator 73 will provide an output on lead 80. Thelead 80 is coupled to a logic enable latch 74.

As seen from FIG. 7 the end point counter 72 receives a high frequencyscanning pulse train from oscillator 77. Oscillator 77 may be a highspeed astable multivibrator. In this manner the end point counterinterrogates each latch as 1 to 10(0) in sequence in a rapid manner.Each time a latch changes state and goes from a no clot to a clotposition, the counter increments by one count and therefore during ascanning period will detect the number of latches as 71 which changedata. Each latch is also coupled and associated with a respective clotindicator 43. The indicators 43 as shown in FIG. 7 and in FIG. 4 may beLED devices or any other suitable device to give an indication of whichtest chamber provided a clot. The oscillator 77, as will be explained isactivated by the logic enable latch 74 which also serves to activate themotor 78.

The motor 78 is mechanically coupled to the keying member 60 of thecartridge 50. The motor 78 operates at a relatively low RPM which mayfor example, be 0.1 RPM to rotate the cartridge upon activation. Theoutput of the oscillator 77 is also divided by means of a binary divider90 which may comprise a series of cascaded binary multivibrators toprovide a clock signal to display driver 75. Essentially, the counterand display driver 75 receives the clock signal from divider 90 andcounts in seconds. In this manner, if the input to the counter anddisplay driver 75 is a 1 Hz waveform, the counter will count in seconds.One output of the counter and display driver 75 is coupled to a digitaldisplay 42 which may be an LED or LCD display and will display secondsin a direct digital readout. Another output from counter 75 is directedto one input of a second data comparator 76. The comparator 76 receivesother inputs from the thumbwheel switch 44.

Switch 44 is a series of four thumbwheel switches which are coded andwhich enable the operator to select any predetermined time period as forexample, from 0000 to 9999 seconds. The data comparator 76 will comparethe time stored in counter 75 with the setting of the thumbwheel switchbank 44 and will provide an output to trigger the enable latch 74 if anyclot was detected during this time interval. For example, as seen inFIG. 7 there is shown a latch 91 which receives a trigger input from theend point counter 72. This signal to latch 91 is the clot input signaland will trigger latch 91 whenever any clot is detected.

The triggering of latch 91 enables ANDgate 81 which therefore allows thedata comparator 76 to effect the latch 74. The switch 92 may be includedto automatically set latch 91 so that gate 81 is always enabled tothereby allow the latch 74 to be triggered by either the data comparator73 or data comparator 76. Also shown in the circuitry is a reset pulsegenerator 79. The generator 79 is associated with chamber 57 ofcartridge 50 and this will produce a pulse when light source 58 isblocked from sensor 59 during the filling of the cartridge 50 with ablood sample. As soon as blood enters chamber 57 the reset pulsegenerator 79 produces an output pulse which initially resets latches 71,latch 91 and counter display driver 75 to the all zero state or thereset state to enable the start of a test procedure. The pulse generator79 also triggers the latch 74 which now energizes the photosensors 63and applies operating power to the motor 78.

The above described logic diagram may be implemented in many ways asshould be understood by those skilled in the art. Essentially, a biassource is not shown and the entire unit may be battery operated or mayderive power from the AC lines as is conventional. It is also understoodthat the blood sample in cartridge 50 may be preheated by using anordinary heating element incorporated in a temperature control system.The heating of a blood sample is conventional and can easily beaccomodated by well-known circuitry which in essence is not consideredas a part of this invention.

Essentially, the logic circuitry as depicted in FIG. 7 can beimplemented by presently available integrated circuit components and mayemploy a conventional type of logic system such as TTL devices. See forexample a text book entitled TTL Cookbook by D. E. Lancaster publishedby Howard W. Sams Co. (1974). This text book has many examples ofsuitable logic circuits which can be employed in the logic depicted inFIG. 7. Accordingly, the counter/display driver 75 and data comparator76 may be implemented by an integrated circuit component designated asthe ICM7217 sold by the Intersil, Inc. The latches as 71 may beimplemented by utilizing a two input NANDgate quad circuit as the 7400with two element arranged as a latch.

The switches and the remaining circuits are all available in integratedcircuit form from a wide variety of sources. It is of course alsounderstood that one can implement the above described logic functions bymeans of a microprocessor using a suitable program and hardwareconfiguration. See a text entitled Microprocessor and Microcomputers byB. Soucek, published by John Wiley & Sons (1976).

Again, referring to FIG. 7 the operation of the analyzer system is asfollows: Test cartridge 50 is fully inserted into the test well 41. Theextending tab 48 and nozzle 52 protrude slightly from the test well toenable the operator to insert a syringe 31 containing a blood sampleinto the cartridge 50. The unit, of course, may provide a suitableprewarming period to allow the cartridge and therefore the blood sampleto reach incubator temperature. As the blood sample enters the entrychamber 55 of cartridge 50, it is caused to flow along the lower mostside of the test cartridge 50 as shown in FIG. 5A. Upon reaching eachannular wall as 56 a pool of blood is formed in each test chamber untilthe depth of pool exceeds the height of the wall 56 whereby the bloodoverflows into the next chamber and so on.

When the blood sample reaches the overflow chamber 57, light from source58 is blocked from sensor 59. When this occurs sensor 59 triggers thepulse generator 79. The triggering of generator 79 resets the logicenable latch 74, latches 71, latch 91 and the counter/display driver 75.The triggering of the enable latch 74 provides power to oscillator 77,motor 78 and the photosensors 63. In this manner, the counter 75 beginsto count and the display 42 will display the count in seconds. The testcartridge 50 as coupled to the motor begins to rotate about its axis asshown in FIG. 6A. Light which is projected from sources 62 and receivedby photosensors 63 causes the data latches 71 to be held in the resetcondition which is analogous to a no clot condition. Hence, the clotindicators 43 do not indicate the presence of the clot. However, asshown in FIG. 6B, when clotted blood blocks the light in a test chamberthen the associated latch is caused to change state. Simultaneously,with the change of state, the particular clot indicator 43 isilluminated and the end point counter 72 detects this condition andincrements one count for one latch operation. This also triggers latch91 which enables data comparator 76 to control the enable latch 74.

The process of clot detection in other test chambers is continued untilthe analysis is terminated by the triggering of the logic enable latch74. The latch 74 may be triggered by either the data comparators 73 or76. When the latch 74 is triggered, the oscillator 77 is disabled as ismotor 78 and the count stored in counter 75 is displayed by the display42 in a constant manner. The state of latches 71 and the correspondingclot indicator lamps 43 are also preserved during this condition.

As indicated above, the setting of switches 44 and 45 establishes themode of operation which will cause the tripping of the logic enablelatch 74. For example, if the number of clots detected equals thesetting of switch 45, then comparator 73 will trigger latch 74 and thetime display on display 42 will be that time in which that number ofclots occurred. If the number of clots does not equal the number ofswitch 45 but at least one clot has occurred then latch 74 will betriggered by comparator 76 through the ANDgate 81 and the time displaywill be the time preset by switch 44. If no clot has occurred then latch91 is not set and the logic enable latch will not be reset to allow theanalysis to continue until a clot is detected. At this time the latchwill be tripped via comparator 76 as any time greater than the time seton switch 44 will cause a reset. Thus the time now displayed on display42 is the time for at least one clot to occur. If no clot occurs withina reasonable time which may be preset and for example may be 800seconds, then equipment is automatically deactivated by a suitabletimeout.

A timeout provision is well-known in the art and may comprise a separatecounter which will provide a signal to trigger latch 74 after apredetermined period as for example, 800 seconds. It is of courseunderstood that if switch 92 is activated then the data comparator 76will provide a pulse at the output at the time set by switch 44. Thus,the setting of thumbwheel switches 44 and 45 establishes the mode ofoperation of the analyzer. When switch 44 is set to all zeros the numberset on switch 45 establishes the condition for the termination of theanalyses. For example, assume switch 45 is set to 5 and switch 44 is setto 0000 and the test cartridge 50 has a blood sample but has noreagents. In this manner, the ten test chambers which contained bloodare simultaneously monitored. The system then essentially performs tenidentical coagulation time tests. The resulting time of termination ofanalysis after detecting five clots or end point approximates theaverage coagulation time for the ten tests.

Similarly, if switch 45 is set to 10(0) and switch 44 is set to 480seconds and test cartridge has premeasured heparin in the test chamberssuch that the final heparin concentration of the blood heparin mixturein a given test chamber may be identified by the numeral product of aconstant and the chamber number, then the analysis termination will beestablished by the setting of switch 44. At the conclusion of the 480second time interval, the lowest number channel or chamber for which theclot indicator is not energized establishes the heparin concentrationrequired to prolong coagulation to at least 480 seconds.

Similarly, assume for example that switch 45 is set to 10(0) and switch44 to 135 seconds. The test cartridge has premeasured protamine in itstest chambers such that the final protamine concentration of theblood-protamine mixture in a given test chamber is equal to the chambernumber itself (i.e. the constant of proportionality is unity). Then atthe conclusion of the 135 second time interval, if the lowest numberedchamber in which a clot has been detected is 3, the preferred protamineneutralizing dose for a patient with a 5700 ml blood volume is theproduct of 3 units per ml and 5700 ml or 17,000 units of protamine.

Thus as indicated, the above indicated system is extremely simple andabsolutely reliable in operation as each chamber is monitored in thecartridge and clots are automatically detected and indicated by theequipment on the basis of the chamber number. The cartridge 50 as shownabove is extremely rugged and simple to use as compared to any prior artcartridge and eliminates the need for an operator to distribute bloodsamples in individual compartments as done in many prior art devices.The logic circuitry employed such as the end point counter 72 assumesthat each clot will be detected sequentially even though clots may occurat the same time. This is due to the scanning technique employed whichassures that each latch as 71 is "locked at" at least once in eachcounter 75 count cycle.

According to FIG. 1 the user upon a detection of a clot in a testchamber can determine a patient's reagent needs by forming the productof the patient's blood volume and the concentration of reagent in thechamber. For example, assume the volume 12a is 0.5 ml, and heparincontent premeasured into each chamber is equal to the product of thechamber number and 0.8 units of heparin (e.g. chamber number 4 contains4×0.8 or 3.2 units of heparin). If after 480 seconds of analyzing ablood sample it is observed that no clots are formed in chambers 3, 4and 5 and that the patient has a blood volume of 5700 ml. This is theblood volume for a male, 165 pounds, 5 feet, 10 inches according toAllen, et al.: "Prediction of blood volume and adiposity in man frombody weight and cube of height" Metabolism 5: 328-345, 1956. Then theheparin dose required to prolong the patient's coagulation time to atleast 480 seconds is equal to the product-chamber, 3; blood volume, 5700ml; and constant, 0.8 units heparin/0.5 ml or 27,360 units of heparin.

It will be understood that the precision of such determination ofheparin dose may be improved by increasing the number of test chamberswith a proportionate reduction of the difference in heparin contentbetween chambers. The ability of the observer to distinguish betweenclotted and unclotted blood, represents the practical limitation to suchmethod of improving the analysis, according to FIG. 3.

I claim:
 1. An article of manufacture for use as a blood specimen sampleholder in performing optical analysis of the coagulation time of a bloodsample, comprising:a longitudinal tubular member fabricated from atransparent rigid plastic having a surface roughness adhesiveness forclotted blood to permit clotted blood to adhere to it, said longitudinaltubular member being symmetrically disposed about an axis and having aclosed bottom and an opened top for receiving a blood sample, saidmember having a plurality of annular walls disposed about the innersurface to form a plurality of chambers with said walls each of apredetermined height and relatively concentric to form a blood samplepassageway from the opened top to the closed bottom, whereby when ablood sample is introduced into said opened top and said member istilted from the horizontal blood will flow into a first chamber until itis filled and overflow over said associated wall into the next chamberand so on until each of said chambers contains a sample pool of saidblood.
 2. The sampler holder according to claim 1, wherein said tubularmember is a cylindrical member.
 3. The sample holder according to claim2, further including keying means coupled to said bottom closed surfaceand adapted to be engaged by drive means for rotating said tubularmember.
 4. The sampler holder according to claim 2, further including anextending tab located on said tubular member and extending above the topopening for allowing one to grasp said tab to lift said tubular member.